Thin Film Battery Structures Having Sloped Cell Sidewalls

ABSTRACT

Solid-state battery structures and methods of manufacturing solid-state batteries, such as thin-film batteries, are disclosed. More particularly, embodiments relate to solid-state batteries having a current collector tab between multiple electrochemical cells. Other embodiments are also described and claimed.

This application claims the benefit of U.S. Provisional PatentApplication No. 62/003,504, filed May 27, 2014, and U.S. ProvisionalPatent Application No. 62/165,101, filed May 21, 2015, and thisapplication hereby incorporates herein by reference those provisionalpatent applications.

BACKGROUND

1. Field

Embodiments relate to electrochemical devices and methods ofmanufacturing electrochemical devices. More particularly, someembodiments relate to solid-state batteries, and in particular thin filmbatteries. Other embodiments are also described.

2. Background Information

Solid-state batteries, such as thin-film batteries, are known to providebetter form factors, cycle life, power capability, and safety, ascompared to conventional battery technologies. However, solid-statebattery structure and manufacturing methods may be improved to furtheroptimize battery performance and packaging.

Referring to FIG. 1, an electrochemical device, such as a solid-statebattery, may include one or more electrochemical cells 100 having asubstrate layer 102, a cathode layer 104, and an electrolyte layer 106.There may also be a barrier layer as shown, between the cathode layer104 and the substrate layer 102. During fabrication of theelectrochemical cell 100, there may be a need to cut or remove materialfrom one or more of the cell layers using a laser.

SUMMARY

It has been discovered that the high energy of typical lasers usedduring fabrication of electrochemical cells, e.g., operations to cut orremove cell materials, may generate heat that causes melting, reflowing,and redeposition of the sheet materials. More particularly, as depictedin FIG. 2, melted materials may be ejected or reflowed and redepositedonto an upper surface of the electrochemical cell 200 as ejected slag202 or along the cut face as a slag layer 204. FIGS. 3A and 3B providemagnified views of a cell surface after laser technology has been usedto melt and cut away material. The figures illustrate a distinct ejectedslag 202 that has redeposited onto the upper surface and a slag layer204 along the cut face.

An issue caused by the ejected slag 202 that is formed over theelectrolyte layer 106 is the risk that the slag layer 202 will become anelectrical short between the cathode layer and the anode layer of acell. This can be explained using FIG. 4, which is a partial side viewof an electrochemical device 400. The electrochemical device 400 mayinclude the electrochemical cell 200 having ejected slag 202 over theelectrolyte layer 106. Furthermore, an anode layer 402 has beendeposited over the electrolyte layer 106. It can be seen that anodelayer 402 may come close to making contact with the conductive slaglayer 204 and ejected slag 202. To avoid this, the anode layer 402 ismasked away from an outer edge of the cell during deposition, so as tomaintain a margin 404 between the ejected slag 202 and the anode layer402.

A problem with adding the margin 404, however, is that it may causeunderutilization of the electrochemical cell area, since it in effectcreates a cathode area with no opposing anode area over the margin 404.This can make the cathode layer 104 appear to have a virtual leak as theelectrochemical device 400 goes through chemical equilibrium at rest.Thus, electrochemical device 400 having the margin 404 may havesub-optimal energy density.

Still referring to FIG. 4, the slag 202, 204 creates a further risk ofelectrical shorting when an anode current collector 406 is placed overthe anode layer 402. To avoid electrical shorting between the cathodelayer 104 and anode current collector 406, through the slag layer 204and ejected slag 202, a z-gap 408 is maintained in a vertical direction,i.e., in the direction of layer stacking. But the z-gap 408 may causeunderutilization of space in the vertical direction, particularly in acase in which multiple electrochemical cells 200 are stacked to form theelectrochemical device 400. Thus, electrochemical device 400 having thez-gap 408 may have sub-optimal energy density.

In an embodiment, an electrochemical device may include a stack of twoor more electrochemical cells, and at least one of the cells may includean insertion void, notch, slot, or other gap feature at an edge or sideof the cell stack (cell sidewall), to receive a tab component, e.g., ananode current collector tab or a cathode current collector tab thatmakes electrical contact with the corresponding anode or cathodeelectrode. This may advantageously improve utilization of the availablez-height for the battery stack, because the tab component now does notadd to the z-height.

In an embodiment, an insertion void at an edge region of anelectrochemical device permits insertion of an anode current collectortab that once inserted becomes electrically connected to respectiveanode layers of a pair of adjacent electrochemical cells. Theelectrochemical device includes a first electrochemical cell having afirst electrolyte layer between a first anode layer and a first cathodelayer in a stack direction. The first electrochemical cell may includean anode contact region and an anode current collector contact region,and the anode contact region may be offset in the stack direction fromthe anode current collector contact region. Furthermore, theelectrochemical device may include a second electrochemical cell havinga second electrolyte layer between a second anode layer and a secondcathode layer. The second anode layer of the second electrochemical cellmay face the first anode layer of the first electrochemical cell. Forexample, the first anode layer may touch or contact the second anodelayer at the anode contact region. In an embodiment, the electrochemicaldevice includes an anode current collector tab between the anode currentcollector contact region and the second electrochemical cell. The anodecurrent collector tab may be disposed in a tab insertion space. Theinsertion void may be between the anode layers of the adjacent cells andhave a distance in the stack direction between one anode and the anodecurrent collector contact region of another anode. The distance may beat least as far as the offset between the anode contact region and theanode current collector contact region, and the anode current collectortab may fill the insertion void across the distance. The anode currentcollector tab may be physically located between the electrochemicalcells, and furthermore, the respective anode layers of theelectrochemical cells may be electrically connected to each other by theanode current collector tab. The anode current collector tab mayphysically contact the first anode layer, e.g., at the anode currentcollector contact region, and/or the second anode layer.

In an embodiment, an insertion void at an edge region of anelectrochemical device, where two adjacent cells are connected, permitsinsertion of a cathode current collector tab that is electricallyconnected to the respective cathode layers of the two connectedelectrochemical cells. In an embodiment, the first electrochemical cellincludes a first cathode layer between a first cathode current collectorand the anode contact region of the first anode layer. The secondelectrochemical cell may include a second cathode layer between a secondcathode current collector and the first anode layer. Furthermore, thefirst cathode current collector and the second cathode current collectormay include respective exposed cathode current collector surfaces facingone another and not covered by the cathode layers or the anode layers.The exposed cathode current collector surfaces may be transverselyoffset from the anode contact region and the anode current collectorcontact region. In an embodiment, the cathode current collector tab isinserted between the exposed cathode current collector surfaces.

Rather than describing the gap feature that receives a tab in terms ofan “insertion void,” etc., the device structure may also be described interms of separation distances between corresponding cell regions, wherethe separation distance may be greater near an edge region of the deviceas compared to a middle region of the device, thereby allowing for acurrent collector tab to be inserted between the cells over the edgeregion without increasing the z-height of the device over the middleregion. In an embodiment, an electrochemical device includes a firstelectrochemical cell and a second electrochemical cell, and each cellhas a respective electrolyte layer between a respective anode layer anda respective cathode layer in a stack direction. The cells may beseparated by a separation distance in the stack direction that variesalong a transverse direction, and the separation distance may be greaternear an outer perimeter of the cells than near a medial portion of thecells. For example, the separation distance over the outer region may besimilar to a thickness of a current collector tab and the separationdistance over the inner region may be essentially zero. In anembodiment, a transition region tapers, e.g., along a ramp, between theouter region and the inner region. The outer region may include an anodecollector contact region and the inner region may include an anodecontact region, and furthermore, the anode collector contact region maybe electrically connected to the anode contact region. In an embodiment,one or more of the anode contact region or the anode collector contactregion includes at least a portion of a respective anode layer.

In accordance with an embodiment of the invention, an electrochemicaldevice having one or more cells includes a cell stack up that includesan electrolyte layer between an anode layer and a cathode layer. Thestack up of the anode layer, the electrolyte layer, and the cathodelayer defines a cell sidewall that has a non-zero, non-vertical slope(or simply, slope). In one embodiment, the cell sidewall is said to besloped in an outward direction, in that a height of the cell sidewalldiminishes versus increasing distance in an outward direction. The anodelayer, the electrolyte layer, and the cathode layer may includerespective sidewalls exposed along the cell sidewall. For example, thecell sidewall may extend from a top surface of the anode layer to theexposed cathode current collector surface, and the exposed sidewalls ofthe layers may be contiguous along the non-zero, non-vertical slope.Thus, the cell sidewall in that region may have a fixed or alternativelya smoothly changing slope. Examples include a cell sidewall whose slopedoes not become zero, or exhibits no discontinuity. In an embodiment,the non-vertical slope may include a linear portion. The non-verticalslope may also include a curvilinear or nonlinear slope portion, insteadof, or in addition to, the linear slope portion. The electrochemicalcell may include additional layers in the cell stack, e.g., a cathodecurrent collector, and the additional layers may include respectiveexposed sidewalls. For example, a cathode current collector may includean exposed sidewall that is contiguous with the other exposed sidewallsof the stack layers along the non-zero, non-vertical slope of the cellsidewall. The cell sidewall may extend from the top surface of the anodelayer to a terminal edge on any other layer, e.g., the terminal edge maybe on the cathode current collector at a location vertically offset froma top surface of the cathode current collector, and the exposed sidewallof the cathode current collector may extend between the top surface andthe terminal edge.

In an embodiment, the cell sidewall having a non-zero, non-verticalslope may be contiguous in that the edges of the adjacent constituentlayers of the cell are coincident. For example, the electrolyte sidewallmay extend between an electrolyte top edge and the cathode layer, wherethe electrolyte top edge may be coincident with a bottom edge of theanode. Another way to describe a cell sidewall as having a non-zero,non-vertical slope is one whose anode bottom edge is laterally offsetfrom the anode top edge, for example in an outward direction.

The sloped sidewall may be obtained by using a controlled, ablationprocess that limits the creation of heat during cutting across thevarious layers of the cell, to thereby avoid formation of the slaglayers mentioned above. For example, the ablation process may beperformed using an ablation laser to result in the cut cell having asloped sidewall, and one that advantageously may be devoid of a slaglayer, thereby avoiding the need for adopting the limited solutionsdescribed above (that cause under utilization of the electrochemicalcell area).

As mentioned above, a controlled laser ablation process that limits thecreation of heat during cutting may be used to fabricate the variouscell and device architectures described below. In an embodiment, amethod includes setting an intensity of a laser beam to a level lessthan required to melt one or more layers of an electrochemical cell. Forexample, setting the intensity may include setting a power of the laserbeam and defocusing the laser beam to achieve the intensity. The methodmay also include lasing the one or more layers of the electrochemicalcell with the laser beam to remove material from the cell layers andexpose layer sidewalls along the cell sidewall having a non-zero,non-vertical slope.

The above summary does not include an exhaustive list of all aspects ofthe present invention. It is contemplated that the invention includesall systems and methods that can be practiced from all suitablecombinations of the various aspects summarized above, as well as thosedisclosed in the Detailed Description below and particularly pointed outin the claims filed with the application. Such combinations haveparticular advantages not specifically recited in the above summary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a sheet of multi-layered material used tomanufacture an electrochemical cell.

FIG. 2 is a side view of an electrochemical cell.

FIGS. 3A-3B are magnified views of an electrochemical cell, illustratingthe redeposition of slag from the cut material.

FIG. 4 is a partial side view of an electrochemical device.

FIG. 5 is a side view of an electrochemical cell in accordance with anembodiment.

FIG. 6 is a side view of an electrochemical cell having a non-verticalsloped sidewall in accordance with an embodiment.

FIG. 7 is a side view of several singulated electrochemical cells formedfrom a sheet of multi-layered material in accordance with an embodiment.

FIG. 8 is a detail view, taken from Detail A of FIG. 7, of an edge of asingulated electrochemical cell in accordance with an embodiment.

FIG. 9 is a top view of an electrochemical device having currentcollector tabs in accordance with an embodiment.

FIG. 10 is a cross-sectional view, taken about line A-A of FIG. 9, of anelectrochemical device having an anode current collector tab inaccordance with an embodiment.

FIG. 11 is a cross-sectional view, taken about line B-B of FIG. 9, of anelectrochemical device having a cathode current collector tab inaccordance with an embodiment.

FIGS. 12-21 are various views of an electrochemical device havingcurrent collector tabs shown at different stages of a manufacturingprocess in accordance with an embodiment.

FIG. 22 is a top view of two electrochemical cells prior to beingstacked to form an electrochemical device in accordance with anembodiment.

DETAILED DESCRIPTION

Structures and manufacturing methods for solid-state batteries aredescribed. However, while some embodiments are described with specificregard to manufacturing processes or structures for integration within asolid-state battery, the embodiments are not so limited, and certainembodiments may also be applicable to other uses. For example, one ormore of the embodiments described below may be used to manufacture otherlayered elements, such as silicon-based solar cells.

The following description is with reference to the figures. However,certain embodiments may be practiced without one or more of thesespecific details, or in combination with other known methods andconfigurations. In the following description, numerous specific detailsare set forth, such as specific configurations, dimensions, andprocesses, in order to provide a thorough understanding of theembodiments. In other instances, well-known processes and manufacturingtechniques have not been described in particular detail in order to notunnecessarily obscure the description. Reference throughout thisspecification to “one embodiment,” “an embodiment,” or the like, meansthat a particular feature, structure, configuration, or characteristicdescribed is included in at least one embodiment. Thus, the appearanceof the phrase “one embodiment,” “an embodiment,” or the like, in variousplaces throughout this specification are not necessarily referring tothe same embodiment. Furthermore, the particular features, structures,configurations, or characteristics may be combined in any suitablemanner in one or more embodiments.

In one aspect of the invention, an electrochemical cell includes severallayers having respective sidewalls that combine to form a cell sidewall.Furthermore, the cell sidewall may include a non-vertical slope. Forexample, the cell sidewall may taper along the respective layersidewalls, e.g., between an anode layer, an electrolyte layer, and acathode layer, such that a height of the cell sidewall diminishes in atransverse direction outwardly from a top surface of the anode layer.The transverse direction may be distinguished from a stack direction (ora vertical direction), in that the transverse direction may beessentially orthogonal to the stack direction. Thus, the transversedirection may be considered to radiate perpendicular to stack axis 1014.An outward direction may be a direction away from a centerline or middleregion of an electrochemical cell or electrochemical device. Thus, anoutward transverse direction is orthogonal to stack axis 1014 locatedalong a centerline of the cell or device. Accordingly, the respectivesidewalls of the electrochemical cell layers may be contiguous, i.e.,the edges of each layer of the electrochemical cell are coincident withedges of a next adjacent layer, thereby forming a contiguous cellsidewall. The non-vertical slope of the cell sidewall may have planarand/or curvilinear portions. Thus, the sloping cell sidewall may providefor a cathode layer that is essentially entirely covered by the anodelayer, and thus, electroactive portions of the cell may be maximized andenergy density of the electrochemical cell may be improved.

In another aspect, an electrochemical device having two electrochemicalcells is provided. In an embodiment, the electrochemical cells arefabricated to include one or more recesses to receive a currentcollector. In an embodiment, both cells include one or more recesses,and in another embodiment, only one of the two cells includes one ormore recesses. As a result of the recesses, a separation distancebetween the cells in a vertical direction varies over a transversedirection. For example, the separation distance between the cells overthe recess area near an outer portion of the electrochemical cells maybe greater than the separation distance between the cells near a medialportion of the cells. In an embodiment, a transition region such as atapered region may be formed between the recessed region and thenon-recessed regions. Furthermore, the recesses may include a portion ofan anode layer or an exposed cathode current collector, i.e., a cathodecurrent collector uncovered by other layers of the cell prior toinsertion of a current collector tab, and the recessed regions may beplaced in electrical connection with respective anode or cathodematerial near the medial region of the cell stack. More particularly, atleast one of the electrochemical cells may include an anode collectorcontact region that is vertically offset in a vertical direction from ananode contact region of the electrochemical cell. Thus, when theelectrochemical cells are apposed to one another, the recesses form agap to facilitate insertion of an anode current collector tab to makeelectrical contact with the anode layers or to facilitate insertion of acathode current collector tab to make electrical contact with thesubstrate layers. The gap may be filled entirely by the tabs, and in anembodiment, the tabs may be encompassed within the outer boundary of theelectrochemical cells, to provide for a square or rectangularelectrochemical device profile when viewed from above. This efficientpackaging of the tabs within the electrochemical device provides foroptimized energy density and a more compact form factor for improvedproduct packaging.

Referring to FIG. 5, a side view of an electrochemical cell is shown inaccordance with an embodiment. The electrochemical cell 500 may includean electrolyte layer 508 between an anode layer 510 and a cathode layer506. The cathode layer 506 may, for example, include LiCoO2, LiMn2O4,LiMnO2, LiNiO2, LiFePO4, LiVO2, or any mixture or chemical derivativethereof. The electrolyte layer 508 may facilitate ion transfer betweenthe cathode layer 506 and the anode layer 510. Accordingly, theelectrolyte layer 508 may be a solid electrolyte, which may not containany liquid components and may not require any binder or separatormaterials compounded into a solid thin film. For example, theelectrolyte layer 508 may include lithium phosphorous oxynitride (LiPON)or other solid state thin-film electrolytes such as LiAlF₄, Li₃PO₄ dopedLi₄SiS₄. The anode layer 510 may, for example, include lithium, lithiumalloys, metals that can form solid solutions or chemical compounds withlithium, or a so-called lithium-ion compound that may be used as anegative anode material in lithium-based batteries, such as Li₄Ti₅O₁₂.

In an embodiment, the cathode layer 506 may be electrically connectedwith a cathode current collector 504, which may be an electricallyconductive layer or a tab. Similarly, the anode layer 510 may beelectrically connected with an anode current collector, which may be anelectrically conductive layer or a tab. Optionally, one or moreintermediate layers may be disposed between the cathode layer 506 or theanode layer 510 and a respective current collector. For example, abarrier film layer 502 may separate the cathode layer 506 from thecathode current collector 504. For example, the barrier film layer 502may be in direct physical contact with the cathode layer 506 and thecathode current collector 504. The barrier film layer 502 may reduce thelikelihood of contaminants and/or ions from diffusing between thecathode current collector 504 and the cathode layer 506. Thus, thebarrier film layer 502 may include materials that are poor conductors ofions, such as borides, carbides, diamond, diamond-like carbon,silicides, nitrides, phosphides, oxides, fluorides, chlorides, bromides,iodides, and compounds thereof. Alternatively, an additionalintermediate layer, such as a substrate layer, e.g., substrate layer102, may be disposed between the cathode layer 506 and the cathodecurrent collector 504. The substrate layer may, for example, provideelectrical connectivity between the cathode layer 506 and the cathodecurrent collector 504 and may also provide structural support, e.g.,rigidity, to the electrochemical cell 500. Accordingly, the substratelayer may include a metal foil or another electrically conductive layer.

In some instances, the electrochemically active layers of the cell maybe formed on one side of the substrate layer, e.g., using materialdeposition techniques such as physical vapor deposition, and the cathodecurrent collector 504 may be formed separately and physically coupled toanother side of the substrate layer. In other instances, theelectrochemically active layers of the cell may be formed on thesubstrate layer, and then the electrochemically active layers may beremoved from the substrate layer and physically coupled to theseparately formed cathode current collector 504. In still otherinstances, the electrochemically active layers of the cell may beformed, e.g., physical vapor deposited, directly on the cathode currentcollector 504. Thus, there are many different ways to create anelectrochemical cell 500 having several electrochemically active layers.

The layers of the electrochemical cell 500 may be thin. For example, thecathode current collector layer 504 may have a thickness in a range ofbetween 10 to 100 μm, e.g., 50 μm. The composite electrochemical cell500 may have a total thickness in a range of between 13 to 300 μm. Forexample, the barrier film layer 502, cathode layer 506, electrolytelayer 508, and anode layer 510 may combine to have a thickness in arange of between 3 to 290 μm, e.g., 25 μm.

In an embodiment, an electrochemical cell 500 may be provided thatincludes every layer of electrochemical cell 500. More particularly, theelectrochemical cell may include cathode current collector 504, barrierfilm layer 502, cathode layer 506, electrolyte layer 508, and anodelayer 510. During fabrication, the layers may be cut using conventionallaser technology to melt through the layers. Accordingly, a slag layer512 may be redeposited along the laser cut outer edge of electrochemicalcell 500.

Referring to FIG. 6, a side view of the electrochemical cell of FIG. 5is shown, having a non-vertical sloped sidewall in accordance with anembodiment of the invention. In an embodiment, the electrochemical cell500 may have material removed to form a cell sidewall 601. For example,a portion of the electrochemical cell 500 may be ablated, etched,skived, ground, etc., using “cold cutting” technologies that removematerial. Cold cutting is a term that is used broadly to refer tomethods that can cut or remove material without melting the materials,but conceivably, slope cell sidewall 601 may be achieved using othercutting methods that employ material melting, and thus, cold cutting isnot intended to be limiting of the invention. Nonetheless, the viableoptions for selectively and controllably eliminating material withoutmelting include laser ablation, which is to be distinguished from lasercutting that produces slag layer 512. More particularly, in a laserablation process, a low-energy, short wavelength, and/or defocused laserbeam may remove portions of one or more layers of material from theelectrochemical cell 500 without melting and redepositing slag. As aresult of the laser ablation process, at least a portion of theresulting slag layer 512 may be removed across the cut surface as seenin FIG. 6, thereby reducing the likelihood of electrical shortingbetween cell layers, e.g., the anode layer 510 and the cathode layer506.

The cell sidewall 601 may be formed along the cut surface. In anembodiment, the cell sidewall 601 includes respective sidewalls of oneor more layers of the electrochemical cell 500. For example, the cellsidewall 601 may extend along a non-zero, non-vertical slope between atop surface 620 of the anode layer 510 to (and optionally includingportions of) the cathode current collector 504. That is, the cellsidewall 601 may extend outwardly from anode top edge 602 of top surface620 to a terminal edge 603. Terminal edge 603 may represent a locationat which the taper of cell sidewall ends and a lateral side ofelectrochemical cell transitions to an infinite, vertical slope. Forinstance, terminal edge 603 may coincide with slag layer top edge 604,which is an upper location along the vertical wall formed by lasercutting electrochemical cell 500. Thus, in an embodiment, the cellsidewall 601 may include a non-vertical slope between a top edge, e.g.,anode top edge 602 and a bottom edge, e.g., terminal edge 603 coincidingwith slag layer top edge 604. That is, the cell sidewall 601 may besloped and a height (in a vertical direction) of the cell sidewall 601diminishes along a transverse direction orthogonal to the verticaldirection. More particularly, the cell sidewall 601 height may diminishin a transverse direction outwardly from an anode top surface having theanode top edge 602 toward the terminal edge 603. The height of the cellsidewall 601 may diminish at a higher or lower rate, however, in anembodiment, the cell sidewall 601 includes a non-vertical slope and thediminution of the height does not occur at an infinite rate as in thecase of a vertical sidewall.

Given that the slope of cell sidewall 601 may vary, and also given thatcell sidewall 601 may be formed by removing material fromelectrochemical cell 500 using an ablation process that can be varied toablate the cell to a desired depth, it will be appreciated that terminaledge 603 of cell sidewall 601 may be located along a sidewall of any ofthe constituent layers of electrochemical cell 500. For example, cathodecurrent collector 504 may have a top surface 650 electrically connectedto cathode layer 506 (cathode layer 506 may be over the top surface 650and on cathode current collector 504). By varying the depth thatmaterial is removed using an ablation process, terminal edge 603 mayterminate at locations more or less offset from the top surface 650 ofcathode current collector 504. For example, as shown in FIG. 6, terminaledge 603 may be offset in the vertical direction from top surface (andbelow top surface 650). When terminal edge 603 is below top surface 650along cell sidewall 601, the cathode current collector includes acathode current collector sidewall 652 that is exposed due to theremoval of material using the ablation process. The cathode collectorsidewall 652 may be contiguous with the other exposed sidewall portions,as described below, to form the non-zero, non-vertical slope of cellsidewall 601.

Less material may be removed during the ablation process to form ashallower cut. Accordingly, the terminal edge may coincide with topsurface 650. That is, cell sidewall 601 may extend along a non-zero,non-vertical slope from anode top edge 602 to terminal edge 603 at topsurface 650. In such case, since the ablation cut does not extend belowtop surface 650 of cathode current collector 504, electrochemical cell500 may lack a cathode current collector sidewall 652.

In an embodiment, cathode current collector 504 includes a bottomsurface 660 below top surface 650. Furthermore, the ablation process maybe varied to remove material across an entire cell height 700 (see FIG.7) of electrochemical cell 500. That is, as shown in FIG. 7, cut trough702 may be driven through electrochemical cell 500 to form cell sidewall601 extending from anode top edge 602 at anode top surface 620 toterminal edge 603 at bottom surface 660. Thus, cell sidewall 601 mayinclude an exposed cathode current collector sidewall 652 sloping fromtop surface 650 to terminal edge 603 at bottom surface 660, as shown inFIG. 7.

In an embodiment, as shown below in the electrochemical deviceembodiments of FIGS. 10-11, terminal edge 603 may be a transition pointat which cell sidewall 601 changes to a zero, horizontal slope. Forexample, cell sidewall 601 may slope from anode top edge 602 to terminaledge 603 below top surface 650 of cathode current collector 504.Accordingly, cell sidewall 601 may include the exposed sidewalls ofanode layer 510, electrolyte layer 508, cathode layer 506, and cathodecurrent collector 504. The ablation cut depth may be shallower, however,than cell height 700, and thus, a horizontal upper surface is formed atthe bottom of the ablation cut. This horizontal upper surface(indicated, in an embodiment, as exposed cathode current collectorsurface 1102 in FIG. 11) may extend from terminal edge 603 to a lateralside of cathode current collector 504. As such, rather than being apoint at which cell sidewall 601 transition to a vertical surface (e.g.,the lateral surface apposed with slag layer 512 in FIG. 6) or a point atwhich cell sidewall 601 transitions to bottom surface 660 (see FIG. 7),terminal edge 603 may be a point at which cell sidewall 601 along a sideof an ablation cut transitions into a horizontal surface along a base ofthe ablation cut.

In an embodiment, the cell sidewall 601 is contiguous across its length.For example, in an embodiment, the cell sidewall 601 tapers between theanode top edge 602 and the slag layer top edge 604, as seen in FIG. 6(which shows an exaggerated taper). The respective sidewalls of theanode layer, electrolyte layer, and cathode layer along the non-verticalslope may be partially or wholly planar. Accordingly, the non-verticalslope may include a linear slope portion. Thus, a slope of cell sidewall601 may be consistent across all layers of electrochemical cell 500.That is, the ablated wall having the slope, i.e., cell sidewall 601, mayhave a continuous and linear slope from anode top edge 602 to slag layertop edge 604.

Rather than having a continuous and linear slope, as shown by a dottedline in FIG. 6, the non-vertical slope may be contiguous but insteadhave a curvilinear portion. For example, curvilinear slope portion 606may follow a curvilinear path, e.g., an arc, between the anode top edge602 and the slag layer top edge 604. In an embodiment, the curvature orshape of the cell sidewall 601 may be controlled by defocusing a laserbeam used for ablation. For example, the laser beam may be defocused tocause a taper of an ablated sidewall to have a taper run, i.e., adistance covered by the cell sidewall 601 in a direction orthogonal tothe vertical direction, of between 5-50 μm, e.g., 20 μm. The laser beamintensity and focus may be controlled to create any range of cut surfacegeometries.

Given that the ablated surface of cell sidewall 601 may be contiguous,each layer of the electrochemical cell 500 may include a top edge and abottom edge, and the top edge of a first layer may be coincident withthe bottom edge of a second layer stacked over the first layer. Forinstance, the anode layer 510 may have an anode sidewall 610 between theanode top edge 602 and the anode bottom edge 608. Furthermore, the anodelayer bottom edge 604 may be laterally offset, i.e., in a transversedirection orthogonal to a vertical direction and outwardly away from atop surface of the anode top surface and the anode top edge 602.Similarly, the electrolyte layer 508 between the anode layer 510 and thecathode layer 506 may have an electrolyte sidewall 612 between anelectrolyte top edge 614 and an electrolyte bottom edge 616, e.g., atthe cathode layer 506. In an embodiment, the electrolyte top edge 614 iscoincident with the anode bottom edge 608, which may make a smoothtransition between the sidewalls of the two layers. It is to beunderstood that a smooth transition does not imply that a tangent of therespective merging sidewalls are parallel, but rather, one sidewall maybe angled with respect to the other sidewall. If the edges of thesidewalls are essentially coincident at the transition between layers,then the transition may be considered to be smooth. Similarly, a topedge of the cathode layer 506 may be coincident with the electrolytebottom edge 616, and so on. Accordingly, the sidewalls of all layers arecontiguous and continuous over the ablated, or otherwise formed, cellsidewall 601 surface. Referring to FIG. 7, a side view of severalsingulated electrochemical cells formed from a sheet of multi-layeredmaterial is shown in accordance with another embodiment of theinvention. This structure may be, but is not necessarily, the result ofa low-energy, short wavelength, and/or defocused laser beam having beenused to cut fully through a multilayered sheet of material, but withoutmelting and redepositing the material to create the slag layer 512. Inother words, rather than singulating the electrochemical cells 500 bymelting through the sheet with a typical laser cutting process and thenablating the sidewalls to remove the slag layer 512, the sheet mayinstead be singulated using a cold cutting technology, e.g., a laserablation process, that removes material without melting and redepositingthe material in the first place. The sheet of multi-layered material maybe singulated using an ablation laser, e.g., a laser that has been tunedfor ablation rather than for cutting. The intensity of the laser beammay also be adjusted to reduce the taper angle shown in the figure,while driving a cut trough 702 fully through the sheet, from the anodelayer 510 down through the cathode current collector 504. Such cuttingthrough ablation, rather than melting, may mitigate or even reduce thelikelihood of slag redeposition along the resulting cut edge and alsothe top surface of the singulated cells. The cutting tool, e.g., a laserbeam, may be used to generate a gap between adjacent cell sidewallswhere material has been removed. Furthermore, the gap may be definedbetween the cell sidewalls 601, and each cell sidewall 601 may include anon-vertical sloped surface, e.g., the slope may include at least aplanar or curvilinear slope portion. Note that ablation is only onemanner of creating a contiguous sloped surface without melting andredepositing the cut or removed material, and thus, is not limiting ofthe invention. Furthermore, other embodiments may allow for typicallaser cutting technologies to melt through layers of an electrochemicalcell and to still create the non-vertical sloped sidewall surfacedescribed herein.

Referring to FIG. 8, a detail view, taken from Detail A of FIG. 7, of anouter edge of a singulated electrochemical cell is shown. The cut mayleave a contiguous taper from the anode top edge 602 through every layerfrom the anode layer 510 down through the cathode current collector 504.A slope of cell sidewall 601 along the ablation cut may be consistentacross all layers of electrochemical cell 500. That is, the ablated wallhaving the slope, i.e., cell sidewall 601, may have a continuous andlinear slope from anode top edge 602 to a bottom edge of the layerforming cathode current collector 504. Thus, each layer of thesingulated electrochemical cell 500 may include a sidewall thattransitions smoothly into an adjacent layer sidewall. In an embodiment,for each layer sidewall the top and bottom edges are coincident withadjacent sidewall edges, meaning that there may be essentially nodiscontinuity as the sidewalls transition from one layer to the next.This is in contrast to what is shown in FIG. 4, where a margin 404 isformed between the sidewalls of the adjacent anode layer 402 andelectrolyte layer 106.

As a result of the processes and electrochemical cell structuresdescribed above, a proportion of the cathode layer 506 having anodelayer 510 overlying it, may be increased. The proportion may vary basedon an angle of the sidewall slope, but for any given slope angle, theproportion may be maximized. That is, for any given sidewall slope, theanode layer 510 may extend fully to a lateral edge of theelectrochemical cell 500, i.e., there may be little or no margin betweenan electrolyte sidewall 612 and an anode sidewall 610. For example, anymargin or lateral offset between the sidewalls 610, 612 may be less thana thickness of the anode layer 510, e.g., less than 20 μm. Thus, theelectrochemical cell surface area in a direction orthogonal to thevertical direction may be essentially fully utilized and anode area maybe maximized. More particularly, the electrochemical cell 500 may have astructure in which practically the entire cathode layer 506 is apposedby an anode layer 510 across from the electrolyte layer 508 as a resultof the sidewall having a contiguous slope between the cathode layer 506and the anode layer 510. Thus, a bottom surface area of an anode areamay be essentially equal to an upper surface area of the cathode layer506, the difference being determined by the sidewall slope between theareas, resulting in substantially no virtual leak observed in thecathode as the electrochemical cell 500 goes through chemicalequilibrium at rest. By maximizing the proportion of cathode havinganode overlying it in this way, an increase in performance of up to 20%may be achieved over masking methodologies that form a margin betweenthe anode and cathode edges, as described with respect to FIG. 4 above.In addition to improving battery performance, a contiguous sidewallsurface with a maximized anode surface area may also be moremanufacturable, since no masking is required. In the case of singulatingelectrochemical cells using a cold cutting technology, e.g., laserablation, as opposed to masking and laser cutting, cut trough may havecloser tolerances or be narrower than may be achieved with masking. Thismay reduce material waste and manufacturing cost, as compared toexisting masking and patterning techniques, which are generally tooflimsy or time-consuming to achieve such thin cut troughs 702.

As described above, in an embodiment, cold cutting to singulate anelectrochemical cell 500 from a sheet of multi-layered material, or topattern or ablate the electrochemical cell 500, e.g., to remove the slaglayer 512 to reduce the likelihood of shorting between layers, may beachieved using an ablation laser. A laser beam in a wavelength spectrumbelow 550 nm may be used to ablate and remove material from the sheet orelectrochemical cell 500. For example, a green or ultraviolet wavelengthlaser beam having a wavelength of 530 nm may be used to ablate the oneor more layers of electrochemical cell 500. Furthermore, an intensity ofthe short wavelength laser beam may be controlled to reduce thelikelihood of melting of the material layers. That is, the intensity ofthe laser beam may be controlled to generate heat that is absorbed inthe multilayered material, causing ablation of the material rather thanmelting of the material. In an embodiment, laser beam intensity may becontrolled by adjusting a power setting of the laser beam.

Intensity of the laser beam used to ablate the multilayered sheet mayalso be controlled by adjusting a focal area of the laser beam. Morespecifically, the laser beam may be defocused. Accordingly, the focalarea at the surface of the multilayered sheet is increased, therebyreducing laser beam intensity at a given point. In an embodiment,defocusing the laser beam changes the geometry of the resulting cutsurface, and thus, the cell sidewall 601 slope angle or shape. Forexample, as the laser beam is further defocused, a taper angle of thecell sidewall 601 may increase. That is, defocusing the laser beam maycreate a larger taper run.

Referring to FIG. 9, a top view of an electrochemical device havingcurrent collector tabs is shown in accordance with an embodiment. In anembodiment, an electrochemical device 900 may be manufactured to includecurrent collector tabs, e.g., an anode current collector tab 902 and acathode current collector tab 904. More particularly, an electrochemicaldevice 900 may be formed that includes at least two electrochemicalcells 500. In an embodiment, each electrochemical cell 500 includes ananode layer 510, an electrolyte layer 508, a cathode layer 506, and acathode current collector 504, as described above. Each cell may, butneed not, maximize the proportion of cathode area having an anode areaoverlying it, by incorporating a contiguously sloped sidewall havingessentially no margin between layers that are immediately next to oneanother. In an embodiment, the architecture includes tabs that can fitwithin an outer boundary of the electrochemical cell 500, e.g., within asquare or rectangular cell profile when viewed from above. This fitprovides for efficient packaging that may be more easily incorporatedinto products. In an embodiment, separation spaces 906 may be providedbetween the tabs 902, 904 and an adjacent cell body 908 to reduce thelikelihood that electrical and/or ionic shorting will occur between thesides of the tabs and any of the layers, e.g., a sidewall of the anodelayer, cathode layer, or electrolyte layer, that may be exposed andfacing the tab sides.

Referring to FIG. 10, a cross-sectional view, taken about line A-A ofFIG. 9, of an electrochemical device having an anode current collectortab is shown. In one embodiment, the electrochemical device 900 includesa stack of electrochemical cells 500. For example, a firstelectrochemical cell 1002 may be inverted and stacked on a secondelectrochemical cell 1004 such that respective anode layers 510 of theelectrochemical cells 1002, 1004 face one another.

In an embodiment, the electrochemical device 900 includes an insertionvoid 1006 to receive an anode current collector tab 902 between theanode layers 510, without increasing z-height of the assembled device.More particularly, the electrochemical cells 500 may be formed such thatafter assembly, a gap or opening is provided near an edge of theelectrochemical device 900 to receive the anode current collector tab902. The anode layers 510 over the majority of the electrochemicaldevice's transverse area, e.g., over a medial portion of theelectrochemical device, may be either adjacent or abutted with oneanother. For example, the anode layers may be immediately next to eachother, e.g., in physical contact with each other, over at least aportion of their respective areas. Alternatively, there may be a thinseparation layer between the anode layers, such as an electricallyand/or ionically insulating layer. The separation layer may have athickness less than a height of gap or opening provided to receive theanode current collector tab 902. Thus, in an embodiment, z-height may bereduced, even though it may not be reduced to zero. In addition toreducing z-height, the device architecture may allow for thicker tabs tobe used, which may increase the robustness of the tabs and makeelectrical and physical connections to external components morereliable.

Each electrochemical cell 500 may include an anode current collectorcontact region 1012 near an outer perimeter or sidewall. The anodecurrent collector contact regions 1012 may be separated by a distance inthe stack direction sufficient to receive anode current collector tab902. For example, anode current collector tab 902 may be inserted suchthat a distal end extends inward from the sidewall of the cells. Theinner surface of the cells along the anode current collector contactregion 1012 may transition, e.g., taper, over a transition region 1010.That is, in an embodiment, top surface 620 of respective anode layers510 of the stacked electrochemical cells may taper along a non-zero,non-vertical slope across transition region 1010. More particularly, theseparation between cell inner surfaces may reduce over the transitionregion 1010. As a result, a gap may exist between inner surfaces of thecells over transition region 1010, since the anode current collector tab902 may be thicker than the separation distance, and thus, not extendinto the transition region. Note that the taper over the transitionregion 1010 as shown in FIG. 10 is exaggerated, and that a taper run ofthe transition region may be a fraction of the taper rise. In anembodiment, the taper may be essentially vertical, but may include anon-zero slope, such that the transition region 1010 is very small, andthe anode current collector contact region 1012 is essentially directlynext to the anode contact region 1008.

Note that the taper over transition region 1010 may include a verticalrise, and thus, the anode contact region 1008 of each electrochemicalcell may be offset in the stack direction from the respective anodecurrent collector contact region 1012 of the cell. Over the anodecontact region 1008, a separation between the inner surfaces of thecells may be less than over the anode current collector contact region1012. That is, the cells may be separated less over a medial portion,i.e., inward from the transition region 1010, than over an edge region,i.e., over the anode current collector contact region 1012. In oneembodiment, a separation distance between the inner surfaces of thecells over the anode contact region 1008 may be essentially zero and theseparation distance between the inner surfaces of the cells over theanode current collector contact region 1012 may be equal to a thicknessof the anode current collector 902. Thus, an insertion void may beformed between cells over both anode current collector contact region1012 and transition region 1010. Accordingly, the respective anodelayers over the anode contact region 1008 may be directly in electricalcontact. Alternatively, the anode layers may be placed in electricalcontact through an electrically conductive material that is also runningin a same direction as one or more of the anode layers over the anodecontact region 1008, e.g., horizontally or transversely.

In an embodiment, the separation between the inner surfaces of the cellsover the anode current collector contact region 1012 may be formed byremoving a portion of one or more of the respective cathode layers 506of first electrochemical cell 1002 and second electrochemical cell 1004.More particularly, the cathode material may be removed at the peripheryof the cell to make space for the anode current collector tab 902.Another way to describe this is that a notch or slot has been formed ina cell sidewall where at least two stacked cells are joined. Formingsuch a gap feature may result in the inner surface of the cell, which islocated in the notch, to be lined with anode layer material that iselectrically in contact with both of the respective cell anode layers510 (and an anode current collector tab 902 placed within the gapfeature may therefore be in contact with those anode layers).

For completeness of understanding of the above description, another wayto describe an embodiment of the electrochemical device 900 is asfollows. While the anode layer, the electrolyte layer, and the cathodelayer, in a conventional structure, all run horizontally outward,essentially as transverse layers, until they end at the same distance,thereby defining a vertical cell sidewall as seen in FIG. 5 for example,the cathode layer 506, in accordance with an embodiment of theinvention, stops short (does not run all the way out to the cellsidewall as otherwise defined by the side or periphery of a substrate).This in effect creates a gap in the cell sidewall (making up all or partof an insertion void 1006). The electrolyte layer 508 and the anodelayer 510, however, continue to run and conform to the surface of thecathode 506 in the gap, as seen in FIG. 10. The gap need not have anyparticular shape, but it may be large enough to allow an anode currentcollector tab 902 to be positioned at least partially inside so as tomake electrical contact with the anode layers 510. The anode currentcollector tab 902 may therefore fill the insertion void 1006 between theanode current collector contact regions 1012 of the anode layers, i.e.,may fill a distance in the stack direction between the anode currentcollector contact region on an anode layer and a top surface of anopposing anode layer.

It will be appreciated that the embodiment represented in FIG. 10illustrates a “balanced” insertion void 1006, when equal amounts ofcathode layer 506 are absent over an edge region of the stacked cells.However, the contribution to the insertion void 1006 may alternativelybe imbalanced, where, for example, only the cathode layer 506 of firstelectrochemical cell 1002 is absent or notched out over the edge region(which may encompass the anode current collector contact region 1012 andthe transition region 1010) while the other cathode layer 506 of secondelectrochemical cell 1004 (and its anode layer 510 and electrolyte layer508) may extend continuously transverse across those regions, i.e.,without showing any vertical offset. Accordingly, an anode currentcollector 902 with half the thickness may still fit within such animbalanced insertion void 1006. In the case of either a balanced or animbalanced insertion void 1006, the insertion void 1006 may have adistance, e.g., a height in the stack direction of stack axis 1014, thatis at least as far as the offset in the stack direction between the topsurface 620 along anode contact region 1008 and the top surface 620along anode current collector contact region 1012.

The anode current collector tab 902 may be inserted into the insertionvoid 1006 and physically coupled with the inner surface of the cellsover the anode current collector contact region 1012. For example, anodelayers 510 of the electrochemical device may extend over the anodecurrent collector contact region, and thus, the anode layers 510 may bebonded to the anode current collector 902. A physical connection betweenthe anode current collector tab 902 and the anode layers 510 may be madein various manners, including by using an adhesive, e.g., a conductivepressure sensitive adhesive, to create an adhesive bond between surfacesof the physically connected components. Alternatively, a friction fitbetween the anode current collector tab 902 and the anode layers 510 maybe formed. Furthermore, other techniques, such as thermal welding of theanode current collector tab 902 to the anode layers 510 may be used.

In an embodiment, only one of the electrochemical cells in anelectrochemical device 900 includes anode current collector contactregion 1012 offset from the anode contact region 1008. That is, a recessmay be formed in only one electrochemical cell to provide an insertiongap 1006 for insertion of an anode current collector tab 902.Furthermore, it is not necessary that one or more layers of theelectrochemical cells extend fully to the perimeter of the cell, asshown in FIG. 10. For example, one or more of the respective anodelayers 510 in the electrochemical device 900 may not extend fully overthe anode contact region 1008 and the anode current collector contactregion 1012. For example, the anode layer 510 may extend over the anodecontact region 1008 without also extending over the transition region1010 or the anode current collector contact region 1012. Nonetheless,electrical contact may be made between those regions to permit aninserted anode current collector tab 902 to be electrically connected toan anode layer 510 over a portion of the anode contact region 1008. Forexample, an electrically conductive layer, lead, via, etc., may be usedto form an electrical connection between the anode current collectorcontact region 1012 and the anode material within the anode contactregion 1008. Thus, illustration of the anode layer 510 extending fullybetween and over regions 1008, 1012 over transition region 1010 is notintended to be limiting of the invention. Rather, electrochemical cellswith different architectures may be used if a separation distancebetween the electrochemical cells is higher over a region 1012 than at aregion 1008 to allow for insertion of a current collector tab withoutincreasing z-height.

Referring to FIG. 11, a cross-sectional view, taken about line B-B ofFIG. 9, of an electrochemical device having a cathode current collectortab is shown in accordance with an embodiment. In an embodiment, theelectrochemical device 900 includes an insertion void 1006 to receive acathode current collector tab 904, between the cathode currentcollectors 504, without increasing z-height of the assembled device.More particularly, the electrochemical cells 500, i.e., firstelectrochemical cell 1002 and second electrochemical cell 1004, may beformed such that after assembly, a gap or opening is provided near aperimeter region of the electrochemical device 900 that receives thecathode current collector tab 904. The gap or opening may be the resultof vertically recessed surfaces in one or both of the matingelectrochemical cells 1002, 1004. That is, one or both of theelectrochemical cells 1002, 1004 may include recessed substrate surfaces1102 as described further below. Thus, each electrochemical cell 500 mayinclude respective exposed cathode current collector surfaces 1102facing one another and located laterally outside of the various otherlayers of the cell. The cathode current collector surfaces 1102 facingone another to make electrical contact with an inserted currentcollector are exposed because they may not be covered by the otherlayers of the electrochemical cell 500. The various other layers, e.g.,the barrier film layer 502, the cathode layer 506, the electrolyte layer508, and the anode layer 510, of each electrochemical cell 500 in thestack, may include a cell sidewall 601 that is contiguous, and mayinclude a non-zero, non-vertical slope, as described above. Thus, thecathode layer 506 may be essentially fully covered by an overlying anodelayer 510 to increase energy density. The cathode current collector tab904 may be inserted into the insertion void 1006 and bonded to thecathode current collectors 504 of the electrochemical device using,e.g., a conductive pressure sensitive adhesive. The cathode currentcollector tab 904 may contact the exposed surface of the cathode currentcollectors 504, i.e., may be in direct contact with the cathode currentcollectors 504, to facilitate electrical conductivity therebetween.Furthermore, the cathode current collector tab 904 may fill theinsertion void 1006 to fully utilize lateral and vertical space withinthe electrochemical device. This may allow for the tab to fit within theouter boundaries of the stack. It should be clarified that by fittingwithin the outer boundaries of the stack, it is meant that the tab mayextend outward and away from a contact point between cells of theelectrochemical device 900 and that the shape of the tab fills in ordefines an outer boundary of the stack that may be recognized as asimple shape. For example, without the tabs in place, the stack may berecognized from above as having a square profile with notched corners,but upon insertion of the tabs, the stack may be recognized as a havinga square profile. However, a square profile is provided by way ofexample only, and in other instances, insertion of the tabs may definean outer boundary of the electrochemical device 900 having any generalshape, e.g., any regular convex polygon shape. Accordingly, in anembodiment, an electrochemical device having tabs and an outer boundarywith a square profile is achieved.

Advantageously, an electrochemical device having architecture asillustrated in FIGS. 10 and 11 allows for a reduction in a z-height ofthe electrochemical device, thereby improving material energy density.The reduction in z-height may come at the expense of reducing materialin an x- or y-axis direction, i.e., orthogonal to the stack axis 1014,to yield the insertion void 1006, but such reduction in the direction ofthe x-y plane may be proportionally less impactful in terms of batteryperformance degradation. Thus, the illustrated electrochemical devicearchitecture may provide a benefit over current electrochemical devicearchitectures that include, e.g., an anode current collector layerbetween the anode layers 510, which adds additional height to theelectrochemical device stack. An example of a manufacturing process forbuilding an electrochemical device structure as shown in FIGS. 9-11 isdescribed further below.

Referring to FIG. 12, a top view of a precursor cell used during themanufacture of an electrochemical device is shown in accordance with anembodiment. A precursor cell 1200 may be provided. The precursor cellmay have, e.g., a square or rectangular profile, although the profilemay be shaped otherwise. The precursor cell 1200 may be, but is notnecessarily, singulated from a sheet of multi-layered material usinglaser cutting technologies, including an ablation laser for performing alaser ablation process.

Referring to FIG. 13, a cross-sectional view, taken about line C-C ofFIG. 12, of a precursor cell is shown in accordance with an embodiment.The precursor cell 1200 may include the cathode current collector 504,the barrier film layer 502, and the cathode layer 506, having thematerial and structure described above. Thus, in an embodiment, theprecursor cell 1200 represents a state of manufacturing prior todeposition of the electrolyte layer 508 and the anode layer 510. In anembodiment, the precursor cell 1200 has a contiguous sidewall. That is,the sidewall of each layer may be flush with that of another, creating asmooth transition across the entire sidewall face of the cell 1200. Theface may have a planar surface and/or a curved surface. Furthermore, inan embodiment, there is no slag layer over the face of the sidewall;this may be achieved using laser ablation as described above, tosingulate the precursor cell 1200 from a sheet of multi-layeredmaterial.

Referring to FIG. 14, a top view of a precursor cell having an ablatedanode current collector contact region is shown in accordance with anembodiment. In an embodiment, a cold cutting technology, such as anablation laser, is used to remove a portion of one or more of the layersof the precursor cell 1200 in an anode current collector contact region1012. For example, a region having a width and/or length one-tenth of awidth of the precursor cell 1200 may be ablated, although other widthsand/or lengths are alternatively possible.

Referring to FIG. 15, a cross-sectional view, taken about line D-D ofFIG. 14, of a precursor cell having an ablated anode current collectorcontact region is shown in accordance with an embodiment. As describedabove, the precursor cell 1200 may be ablated to remove portions of thecathode layer 506 and the barrier film layer 502. Some portion of thecathode current collector 504 may also be ablated. Thus, an anodecurrent collector contact region 1012 on an upper surface of the cathodecurrent collector 504, as well as a sidewall 1502 along an ablatedsurface of the cathode layer 506 and the barrier film layer 502, may beformed. The sidewall 1502 may include a non-vertical slope extendingbetween a cathode top edge 1504 and the anode current collector contactregion 1012. The sidewall 1502 slope may have a planar surface or acurved surface and be contiguous across the various ablated layers, asdescribed above. Note that at least a portion of cathode currentcollector 504 may be a sloped sidewall between anode current collectorcontact region 1012 and barrier film layer 502. Thus, the anode currentcollector contact region 1012 may be formed by only partially ablatingthrough precursor cell 1200, i.e., the laser ablation process may removematerial from a top surface of precursor cell 1200 to the anode currentcollector contact region 1012 on cathode current collector 504 withoutcutting through the entire thickness of precursor cell 1200 as may bethe case in a traditional laser cutting process.

Referring to FIG. 16, a top view of an electrochemical cell having theanode current collector contact region offset in a vertical direction isshown in accordance with an embodiment. FIG. 17 is a cross-sectionalview, taken about line E-E of FIG. 16, showing how an anode currentcollector contact region 1012 may be recessed in a vertical direction(vertical direction as seen in the figure). The electrolyte layer 508and the anode layer 510 are deposited over the cathode layer 506 of theprecursor cell 1200. Deposition of the layers may be achieved usingknown processes, such as physical vapor deposition or other suitabletechnique. In this case, each of the electrolyte layer 508 and the anodelayer 510 are formed with uniform thickness across the entire uppersurface area of the precursor cell 1200, including over the previouslyablated anode current collector contact region 1012 and the slopedportion of cathode current collector 504 between anode current collectorcontact region 1012 and barrier film layer 502. Deposition, coating,etc., of the electrolyte layer 508 and the anode layer 510 may uniformlycover the underlying anode current collector contact region 1012, i.e.,the exposed cathode current collector 504, to form an upper surface ofelectrochemical cell 500, having an anode layer 510 with the anodecontact region 1008 as indicated, and the anode current collectorcontact region 1012. In one embodiment, the anode layer 510 is the samethickness over its surface area and follows the tapered region betweenthe cathode top edge 1504 and the anode current collector contact region1012, thereby resulting in a top surface of the anode layer 510, whichis located directly over the anode current collector contact region1012, to be vertically recessed in a vertical direction below a topsurface of the anode layer 510 that is located directly over the anodecontact region 1008.

Referring to FIG. 18, a top view of the electrochemical cell having acathode current collector tab region that is offset in a verticaldirection (from an anode layer) is shown, wherein a corner of theelectrochemical cell 500 that is opposite from the anode currentcollector contact region 1012 is ablated to expose the cathode currentcollector 504 and form a cathode current collector tab region 1802. Seethe cross-sectional view, taken about line F-F of FIG. 18, in FIG. 19.Similar to the creation of the vertically recessed anode currentcollector contact region 1012 (see FIGS. 16-17), the layers of theelectrochemical cell 500 may be ablated to remove portions of the anodelayer 510, the electrolyte layer 508, the cathode layer 506, and thebarrier film layer 502. Furthermore, some portion of the cathode currentcollector 504 may be ablated to expose an upper surface of the cathodecurrent collector 504 over a cathode current collector tab region 1802.The exposed cathode current collector surface 1102 may provide a landingfor making electrical contact with the cathode current collector 504.That is, the cathode current collector surface 1102 may be exposed inthe sense that it is not covered by any other layer of theelectrochemical cell 500 prior to tab insertion. However, after a tab isinserted, physical and electrical contact may be made between thecathode current collector 504 and the inserted tab, and thus, at least aportion of the cathode current collector surface 1102 may no longer be“exposed.” Thus, the electrochemical cell 500 may transition from theanode layer 510 to the cathode current collector 504 by removingmaterial to create a sidewall 1502 that slopes in a non-verticaldirection between the anode layer 510 and the cathode current collector504. Note that the sidewall 1502 is illustrated with an exaggeratedtaper angle, i.e., the taper run of the sidewall 1502 may actually besubstantially small as compared to a top surface area of theelectrochemical cell 500, and thus, sidewall 1502 is not apparent in thetop view of electrochemical cell 500 illustrated in FIG. 18. Moreparticularly, the sidewall 1502 may extend between an anode top edge 602and the exposed cathode current collector surface 1102. The sidewall1502 may have a non-vertical sloped surface and be contiguous across thevarious ablated layers, as described above. Also note that at least aportion of cathode current collector 504 may be a sloped sidewallbetween the upward facing exposed cathode current collector 1102 andbarrier film layer 502. Thus, the cathode current collector 1102 may beformed by only partially ablating through electrochemical cell 500,i.e., the laser ablation process may remove material from a top surfaceof electrochemical cell 500 to the exposed cathode current collector1102 on cathode current collector 504 without cutting through the entirethickness of electrochemical cell 500 as may be the case in atraditional laser cutting process.

Referring to FIG. 20, a top view of an electrochemical cell having acathode current collector tab region 1802 that is offset in a verticaldirection is shown. In an embodiment, the anode current collectorcontact region 1012 and the cathode current collector tab region 1802are trimmed back from the perimeter of the electrochemical cell 500,creating an offset in a transverse direction, between an outer perimeteredge 2002 and a tab region outer edge 2004. As described above, such agap may be filled by a respective anode current collector tab 902 orcathode current collector tab 904 during assembly of an electrochemicaldevice to define an outer boundary for electrochemical cell 500 orelectrochemical device 900 that is a simple shape, e.g., a regularconvex polygon shape such as a square. This can be seen in the top viewof the device shown in FIG. 21. More particularly, the tabs can bedescribed as being integrated with the cell structure and sandwichedbetween electrochemical cells, and extend away from the contact regions1012, 1802 to fill the gaps to result in a profile in which outer edge2002 of the cell perimeter and the tab edges 2102 are aligned, e.g., aswhen the electrochemical cell 500 has a square or rectangular profile asseen in FIG. 21.

Referring to FIG. 22, a top view of two electrochemical cells prior tobeing stacked to form an electrochemical device is shown in accordancewith an embodiment. In an embodiment, at least two electrochemical cells500A and 500B include respective first and second tab insertion areas.For example, a first electrochemical cell 500A may include a left tabinsertion area 2200A and a right tab insertion area 2202A. Similarly, asecond electrochemical cell 500B may include a left tab insertion area2200B and a right tab insertion area 2202B. The first electrochemicalcell 500A may be flipped to stack on second electrochemical cell 500B,for example, to form an electrochemical device 900 having facing anodelayers. Thus, in an assembled configuration, the left tab insertion area2200A may face the right tab insertion area 2202B, and the right tabinsertion area 2202A may face the left tab insertion area 2200B.Accordingly, tab insertion areas of first electrochemical cell 500A andsecond electrochemical cell 500B may be minor images of each other withrespect to which type of tab is inserted into left and right tabinsertion areas. That is, tab insertion areas 2200A and 2202B may beconfigured to contact anode current collector tab 902 and tab insertionareas 2202A and 2200B may be configured to contact cathode currentcollector tab 904. In an embodiment, both tab insertion areas of matingtab insertion areas may include recessed contact regions, such as anodecurrent collector contact region 1012 or cathode current collector tabregion 1802 offset in a vertical direction from 1008 as described above.In other embodiments, mating tab insertion areas may include only onerecessed area. For example, first electrochemical cell 500A may includerecessed left tab insertion area 2200A, e.g., a recessed anode currentcollector contact region 1012, and right tab insertion area 2200B, e.g.,a recessed cathode current collector tab region 1802, and the matingleft and right tab insertion areas 2200A, 2202B may not be recessed overthe respective current collector contact regions. As a result, thecurrent collector tabs may fill a vertical space between theelectrochemical cells 500 that is half the separation distance ofinsertion void 1006 in FIGS. 10-11. Nonetheless, z-height may be reducedand the tabs may be recessed into the device in a transverse directionto provide for a device profile in which the outer perimeter edge 2002is aligned with tab outer edges 2102. More particularly, theelectrochemical device of FIGS. 9-11 may be formed.

The present invention also provides the following itemized embodiments:

1. An article of manufacture comprising: several electrochemical cellssingulated from a sheet, wherein adjacent ones of the severalelectrochemical cells are separated by a gap that is tapered.

2. An article of manufacture, comprising: a first electrochemical cellwith a second electrochemical cell, each cell having a respectiveelectrolyte layer between a respective anode layer and a respectivecathode layer in a stack direction, wherein the cells are separated by aseparation distance in the stack direction that varies in a transversedirection, and wherein the separation distance is greater over an outerregion of the coupled cells than over an inner region of the coupledcells.

3. The article of manufacture of item 2, wherein the outer regionincludes an anode collector contact region and the inner region includesan anode contact region, and wherein the anode collector contact regionis electrically connected to the anode contact region.

4. The article of manufacture of item 3, wherein the respective anodelayers extend over one or more of the anode contact region or the anodecollector contact region.

5. A method, comprising: setting an intensity of a laser beam to a levelless than required to melt one or more layers of an electrochemicalcell; and lasing the one or more layers of the electrochemical cell withthe laser beam to form a cell sidewall having a non-zero, non-verticalslope.

6. The method of item 5, wherein the one or more layers include anelectrolyte layer stacked between an anode layer and a cathode layer ina vertical direction, the one or more layers having respective sidewallsmaking up at least a portion of the cell sidewall.

7. The method of item 6, wherein the anode layer includes an anode topsurface, and wherein a height of the cell sidewall diminishes in atransverse direction outwardly.

8. The method of item 7, wherein the respective sidewalls of the anodelayer, the electrolyte layer, and the cathode layer are contiguous alongthe non-vertical slope.

9. The method of item 8, wherein the non-vertical slope includes alinear slope portion.

10. The method of item 8, wherein the non-vertical slope includes acurvilinear slope portion.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope of the invention as set forth in thefollowing claims. The specification and drawings are, accordingly, to beregarded in an illustrative sense rather than a restrictive sense.

What is claimed is:
 1. An electrochemical device, comprising: a firstelectrochemical cell having a first electrolyte layer between a firstanode layer and a first cathode layer in a stack direction, wherein thefirst anode layer includes an anode contact region and an anode currentcollector contact region, and wherein the anode contact region is offsetin the stack direction from the anode current collector contact region;and a second electrochemical cell having a second electrolyte layerbetween a second anode layer and a second cathode layer, wherein thesecond anode layer contacts the first anode layer at the anode contactregion; and an anode current collector tab in contact with the firstanode layer at the anode current collector contact region.
 2. Theelectrochemical device of claim 1 further comprising an insertion voidbetween the anode layers, wherein the anode current collector tab fillsthe insertion void between the anode current collector contact regionand the second anode layer, wherein the insertion void has a distance inthe stack direction between the anode current collector contact regionand the second anode layer, and wherein the distance is at least as faras the offset between the anode contact region and the anode currentcollector contact region.
 3. The electrochemical device of claim 2,wherein a top surface of the first anode layer tapers from the anodecontact region to the anode current collector contact region and the topsurface at the anode contact region is offset in the stack directionfrom the top surface at the anode current collector contact region. 4.The electrochemical device of claim 1, wherein the first electrochemicalcell includes the first cathode layer between the first anode layer anda first cathode current collector, wherein the second electrochemicalcell includes the second cathode layer between the second anode layerand a second cathode current collector, wherein the first cathodecurrent collector and the second cathode current collector includerespective exposed cathode current collector surfaces facing one anotherand not covered by the cathode layers or the anode layers, and whereinthe exposed cathode current collector surfaces are transversely offsetfrom the anode contact region.
 5. The electrochemical device of claim 4further comprising a cathode current collector tab in contact with theexposed cathode current collector surfaces.
 6. The electrochemicaldevice of claim 5, wherein the first anode layer, the first electrolytelayer, and the first cathode layer include respective sidewalls exposedalong a cell sidewall, and wherein the cell sidewall has a non-zero,non-vertical slope.
 7. The electrochemical device of claim 6, whereinthe cell sidewall extends from a top surface of the first anode layer tothe exposed cathode current collector surface of the first cathodecurrent collector, and wherein the exposed sidewalls of the first anodelayer, the first electrolyte layer, and the first cathode layer arecontiguous along the non-zero, non-vertical slope.
 8. Theelectrochemical device of claim 7, wherein the first cathode currentcollector includes a sidewall exposed along the cell sidewall andcontiguous with the other exposed sidewalls of the first anode layer,the first electrolyte layer, and the first cathode layer along thenon-zero, non-vertical slope.
 9. An electrochemical cell, comprising: anelectrolyte layer between an anode layer and a cathode layer in avertical direction, wherein the anode layer, the electrolyte layer, andthe cathode layer include respective sidewalls exposed along a cellsidewall, and wherein the cell sidewall has a non-zero, non-verticalslope.
 10. The electrochemical cell of claim 9, wherein the anode layerincludes a top surface, and wherein a height of the cell sidewalldiminishes in a transverse direction outwardly from the top surfacealong the non-zero, non-vertical slope.
 11. The electrochemical cell ofclaim 10, wherein the respective exposed sidewalls of the anode layer,the electrolyte layer, and the cathode layer are contiguous along thenon-zero, non-vertical slope.
 12. The electrochemical cell of claim 11,wherein the non-zero, non-vertical slope includes a linear slopeportion.
 13. The electrochemical cell of claim 11, wherein the non-zero,non-vertical slope includes a curvilinear slope portion.
 14. Theelectrochemical cell of claim 11, wherein the exposed sidewall of theanode layer extends between an anode top edge on the top surface and theexposed sidewall of the electrolyte layer, and wherein the exposedsidewall of the electrolyte layer extends between the exposed sidewallof the anode layer and the exposed sidewall of the cathode layer. 15.The electrochemical cell of claim 14, wherein the exposed sidewall ofthe cathode layer is offset from the exposed sidewall of the anode layerin the vertical direction and in a transverse direction outwardly alongthe non-zero, non-vertical slope.
 16. The electrochemical cell of claim10 further comprising a cathode current collector having a top surface,wherein the cathode layer is over the top surface of the cathode currentcollector, wherein the height of the cell sidewall diminishes in thetransverse direction outwardly from the top surface of the anode layeralong the non-zero, non-vertical slope to a terminal edge on the cathodecurrent collector, and wherein the terminal edge is offset in thevertical direction from the top surface of the cathode currentcollector.
 17. The electrochemical cell of claim 16, wherein the cathodecurrent collector includes a bottom surface below the top surface of thecathode current collector, and wherein the terminal edge is on thebottom surface and the cell sidewall diminishes from the top surface ofthe anode layer to the terminal edge across a cell height of theelectrochemical cell.
 18. An electrochemical cell, comprising: an anodelayer, an electrolyte layer, a cathode layer, and a cathode currentcollector stacked in a vertical direction, wherein the anode layer, theelectrolyte layer, and the cathode layer include respective sidewallsexposed by removing material from the layers using an ablation process,and wherein the respective sidewalls of the anode layer, the electrolytelayer, and the cathode layer are exposed and contiguous with each otheralong a cell sidewall.
 19. The electrochemical cell of claim 18, whereinthe cell sidewall has a non-zero, non-vertical slope.
 20. Theelectrochemical cell of claim 19, wherein the cathode layer is over atop surface of the cathode current collector, wherein the cathodecurrent collector includes a sidewall exposed by removing material fromthe cathode current collector using the ablation process, wherein thesidewall of the cathode current collector is exposed and contiguous withthe other exposed sidewalls of the anode layer, the electrolyte layer,and the cathode layer, and wherein a height of the cell sidewalldiminishes outwardly from a top surface of the anode layer along thenon-zero, non-vertical slope.